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From: olson@anchor.esd.sgi.com (Dave Olson)
Newsgroups: comp.unix.admin,comp.sys.sgi
Subject: Re: How do I read a bad tape (tar)?
Keywords: tar tape sgi unix
Message-ID: <1991Apr9.030501.23536@odin.corp.sgi.com>
Date: 9 Apr 91 03:05:01 GMT
References: <1991Apr8.231456.391@gpu.utcs.utoronto.ca>
Sender: news@odin.corp.sgi.com (Net News)
Organization: Silicon Graphics, Inc.  Mountain View, CA
Lines: 36

In <1991Apr8.231456.391@gpu.utcs.utoronto.ca> topix@gpu.utcs.utoronto.ca (R. Munroe) writes:


| I am having trouble extracting some important data from a cartridge tape.
| I used tar and now can not retrieve the data.  The tape drive whirrs and
| clicks a couple of times and then the system tells me to insert the next
| tape and press <CR> to continue.  I know the data is on the tape - it justs
| seems that there is a little snag that makes the system think it's
| reached the end of the archive.  Question - is there anyway way of retrieving
| the data (whatever is left of it) by either:
| 
| 1.  Some unix command that will read past the bogus 'end of archive'.
| 
| or
| 
| 2.  Are there any companies that specialize in data recovery that could help.
| 

Unless you are getting kernel messages on the console or in SYSLOG, odds
are VERY high that someone overwrote the beginning of the tape, perhaps
by doing a 'tar c' with no args (fixed in the next release to be a
no op, instead of trashing the tape), when they meant 'tar t'.

If so, there is no hope.  The firmware on the drives refuse to read
past the EOD marker.  Besides, it erased a part of each track when
the the 'tar c', or whatever was done.  This is one of thoese FAQ
that shows up in all the comp groups from time to time.  Remember,
the write protect switch is your friend!

If there were kernel messages of some kind, I might be able to help
you decipher them.
--

	Dave Olson

Life would be so much easier if we could just look at the source code.